Method of making abrasive tools by electro-deposition



June 30, 1910 7 M. MATTIA ETAL 3,517,464

Filed March 19. 1968 INVENTORS MICHAEL MATTIA WILLIAM T. TOMPKINS WzyM "ATTORNEY United States Patent US. Cl. 51--309 1 Claim ABSTRACT OF THE DISCLOSURE An abrasive tool and the method of making such a tool is provided. Particles of grit material are embedded and securely bonded in a layer of metal. The method involves first distributing the grit material on soft material, levelling and embedding the particles into the soft material, electro-depositing the metal around exposed portions of the grit material and removing the soft material.

Abrasive tools including abrasive belts and the like are Well known. In the main, these tools have included abrasive particles adhesively secured to a surface, such as paper or cloth when flexibility is desired as in a belt, or to resin or other solid body, as when grinding wheels and the like are involved. Some of the main problems involved in such abrasive tools are that the grit particles may be subject to excessive wear or may tend to break off their backing surface to which they may be adhered.

When it is desired to machine very hard materials, such as removing rough surfaces from machine tools, or finishing surfaces on other items, the use of the conventional types of grit materials and backings is not practical. In these cases, diamond particles, silicon carbides or other hard material may be used as the grit particles to form the abrasive element.

In the past, diamond chips have been held by bronze or plastic material in abrasive tools. Other metals have also been used to hold the diamond grit material. In the cases where metal has been employed the method of joining the metal and grit material has generally resulted in poor bonding and a subsequent falling away of the grit material from the metal when the abrasive tool is put into use.

In some cases, it is desirable to have the ends of the grit particles projecting from its backing to be in the same relative plane. This is true where fine grinding or finishing is required. Uneven projections of the grit particles may result in scratches in the finished surface of the part being finished.

It is an object of this invention to provide an improved abrasive element.

It is a further object of this invention to provide an improved abrasive element having a metallic backing of improved strength.

It is still a further object of this invention to provide novel methods of making abrasive tools.

It is still a further object of this invention to provide an improved abrasive tool and method for making such tool wherein abrasive grit particles are all in substantially the same plane.

It is still a further object of this invention to provide an improved method of fabricating abrasive tools which may be of contoured shapes.

It is still a further object of this invention to provide an improved abrasive tool wherein the heat conductivity of the backing element is improved.

In accordance with the present invention, an abrasive element is provided. Hard materials of grit particles are intimately bonded to and embedded in metal such as nickel. A method of forming this abrasive element comprises the steps of first depositing the abrasive grit material on to a soft material, such as wax. The grit material is then pressed into the wax so that the projecting edges of the grit material are all in the same relative plane. A resin material is then applied to the wax surface and the projecting grit particles, after which the wax is removed.

After applying a conductive coating to the exposed grit material and the resin, metal is electro-deposited on the particles of grit and the resin. The resin material is then removed and a suitable backing, if needed, is applied to the metal layer.

ings, in which:

FIGS. 1 to 4 illustrate an abrasive tool in accordance with the present invention and the steps of making such a tool.

The present invention will be described in connection with nickel because this metal is used in a preferred embodiment. It is understood, however, that copper, iron or any other type metal which may be electro-deposited may be used without departing from the scope of the invention.

Referring to FIG. 1, particles of abrasive grit 10 which may be diamond chips, silicon carbide or similar type grits, are dispersed on a layer of soft material 12, which may be wax or other suitable material. The wax may be suitably deposited on and supported by a sup ort plate 14. A plate 16 having a fiat surface is pressed against the grit material causing the grit particles to become embedded in the wax. The grit particles 10 are embedded into the wax to different depths depending upon the size of the particles involved. The end projecting portions of the grit particles, however, are at the same level or plane due to the flatness of the surface of the pressure plate 16.

In FIG. 2, there is illustrated a subsequent step in the process wherein the pressure plate 16 is removed and a resin material 18 is deposited on the projecting grit particles and the wax surface in the manner illustrated. The resin material may be deposited by conventional methods, such as pouring the resin while it is in a liquid state and then permitting it to set into a hardened state.

FIG. 3 illustrates a subsequent step in the process. The support plate 14 is removed along with the wax material 12. After the wax material has been removed, a conductive coating 20, which may be a silver coating is applied to the grit particles 10 projecting from the resin material 18 and to the exposed surface of the resin material 18. The silver coating is applied to provide a means for connecting an electrical circuit thereto. The silver coating acts as an electrode to permit an electro-deposition process to take place in a well known manner.

A nickel layer 21 is then deposited on the silver coating and effectively coats the exposed grit particles 10 and resin material 18. The conductive coating is very thin and does not materially form part of the physical structure developed.

One type of deposit metal which may be employed in practicing the present invention would involve the use of nickel deposited from a nickel sulfamate solution. A voltage may be applied to the silver coating which acts as one electrode and to a second electrode (not shown) to cause current to flow and nickel to be deposited on the silver coating.

Referring particularly to FIG. 4, final steps in the method of making the abrasive tool are illustrated. The resin material 18 is removed from the grit and nickel layer 21. A backing 22, which may be flexible or solid, is provided to back up the nickel layer 21. This backing may be resin, plastic, metal or any other suitable backing,

material. The backing is adhered or otherwise suitably placed on the nickel layer.

When the nickel is deposited in the manner illustrated, an intimate bonding between the nickel and the grit particles exists. This results in the particles staying firmly embedded in the nickel with heavy use.

The abrasive tool described may be made flexible by having a relatively thin backing on the nickel layer. Such an arrangement would be useful in flexible belts. On the other hand, the nickel layer may be backed by a thick solid material thereby making the abrasive tool useful in grinding wheels and the like.

It is noted that the invention as described facilitates the making of abrasive tools of complex shapes, such as disks, cups, cones and other irregular shapes. Also, the present invention minimizes the tendency of the space between the cutting surfaces being filled with material from the part being worked. Also, the present invention makes possible abrasive tools which may be made economically.

What is claimed is:

1. A method of forming an abrasive tool having a nickel metal backing with abrasive grit particles embedded therein comprising the steps of providing a layer of relatively soft wax material on a first element having a flat surface, dispersing said grit particles on said layer of soft material, pressing said particles partly into said layer of soft material with a second element having a flat surface a distance insufficient to reach the flat surface of said first element so that the projecting end portions of said particles are in the same plane, with the projecting end portions of said particles not embedde in said soft material being sufiicient to provide cutting edges for said abrasive'tool, applying resin in a liquid state to the surface of said soft material and said particles and permitting said resin to harden, removing said soft material, applying a thin conductive coating of silver for conducting electricity over said grit particles and said resin body, electro-depositing a layer of nickel metal onto said conductive coating, removing said resin, and applying a back ing material to said layer of metal.

v References Cited UNITED STATES PATENTS 2,367,286 1/1945 Keeleric 51--309 2,368,473 1/1945 Keeleric 51309 2,411,867 12/1946 Brenner 51309 2,505,196 4/1950 Mays 51-309 2,571,772 10/1951 Sim0ns 51-309 2,906,612 9/1959 Anthony et a1. 51-293 3,343,932 9/1967 Juillerat 51295 DONALD J. ARNOLD, Primary Examiner v U.S. Cl. X.R. 

